No need for foo="`bar`", foo=`bar` is fine.
Simplify ${foo} and ${1} into $foo and $1.
* acgeneral.m4 (ac_LF_and_DOT): Remove the double quotes.
* acspecific.m4 (AC_PROG_CC_C_O, AC_PROG_F77_C_O): Likewise.
* autoconf.sh: Likewise.
* autoheader.sh: Likewise.
* autoreconf.sh: Likewise.
* autoupdate.sh: Likewise.
* ifnames.sh: Remove all the code and messages related to
AC_MACRODIR, since ifnames is not related to macros in anyway.